1. Technical Field
The present invention relates to an image display device.
2. Related Art
In the past, there have been known projection image display devices (projectors) using a light source such as a laser. In the projection image display devices of this kind, laser beams of the respective color components such as RGB are modulated in luminance in accordance with an image signal, and then combined to display an image. In recent years, it has been required for the projection image display device including other types than the type mentioned above to have a further high resolution and high contrast, and therefore, further improvement of image quality thereof is in progress.
As one of problems such projection image display device with a light source for displaying images should solve, there can be cited deterioration in contrast caused by leakage of light or stray light generated by an optical element forming an optical system. There have been proposed various technologies for preventing the deterioration in contrast. For example, JP-A-2005-17500 (Document 1) discloses a technology in which a movable shield plate is provided to control an amount of light provided to a light modulation element from a light source, thereby reducing the amount of light input when displaying a dark image, thus increasing the contrast in a pseudo manner.
However, since in the technology disclosed in the Document 1 the amount of light of the entire screen is uniformly controlled, there is caused problems that in the case in which a luminescent spot (a light source or a glossy image) exists in a dark image, the luminance of the luminescent spot is reduced, and that a so-called grayish black picture appears.